Dental caries is a progressive condition in which loss of hydroxyapatite mineral reduces the structural integrity of the teeth. Current understanding of dental caries suggests a bacterial etiology which is interdependent upon dietary factors, host defense mechanisms and time. When each of these components are present, dental caries occur. In part, the ability to control dental caries depends upon the effectiveness of oral hygiene treatments including dentifrice and mouth rinse. It is widely acknowledged that caries prevention is dependent upon the compatibility of the components comprising the oral hygiene products. For example, ii is well established that caries are reduced by the addition of fluoride (e.g. sodium fluoride, stannous fluoride, etc.) to a highly compatible dentifrice system. It is also acknowledged that dietary habits, in particular, consumption of carbohydrates such as sucrose can have profound impact on the incidence of dental caries.
Production of acids resulting from plaque's carbohydrate consumption contributes to caries lesion formation. The addition of sweeteners such as sorbitol and, or xylitol to gums, candies and foods have been found to help reduce the incidence of dental caries via significant increases in plaque pH and measurable decreases in plaque S. mutans levels; see U.S. Pat. No. 5,804,165, Arnold, issued Jul. 24, 1996; herein incorporated by reference. The combination of a non-cariogenic sweetener and a suitable fluoride system could provide a potentially powerful approach to controlling dental caries. While caries control has been observed in studies evaluating the benefits of long-term consumption of non-carogenic carbohydrates, bacterial effects have not been consistently shown for all xylitol containing dentifrices.
Some polyalcohols such as glycerol or propylene glycol have been shown to increase antimicrobial activity of hydrophobic preservative compounds such as methyl and propyl p-hydroxybenzoate (parabens). U.S. Pat. No. 5,800,803, Mirajkar et al., issued Feb. 10, 1997, assigned to Colgate, discloses increased uptake of anti-microbials such as triclosan in formulations containing propylene glycol. It is believed that these polyalcohols increase activity via perterbation of the cellular membranes. The degree of membrane perterbation may be related to the hydrophobicity of the polyalcohol. Low molecular weight glycols such as propylene or butylene glycol have also been used as preservatives in both foods and pharmaceutical products. The preservative properties are thought to be manifested through the reduction of water activity. Polyalcohols have also been used as humectants in oral products including dentifrice.